A087177 Number of even partition numbers <= P(n), where P=A000041.

0, 0, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 8, 9, 9, 9, 10, 11, 12, 13, 13, 14, 15, 15, 15, 16, 16, 16, 16, 16, 16, 17, 17, 18, 18, 18, 19, 20, 21, 21, 21, 22, 22, 22, 22, 22, 23, 23, 24, 25, 26, 26, 26, 27, 27, 28, 29, 30, 30, 30, 30, 31, 31, 31, 31, 32, 33, 33

Offset: 0

Author

Reinhard Zumkeller, Aug 23 2003

Keywords

• nonn

Links

• Eric Weisstein's World of Mathematics, Partition Function
• Eric Weisstein's World of Mathematics, Partition Function P Congruences

Crossrefs

Cf. A000041, A052001, A040051, A071754.

Programs

PARI

a(n) = sum(k=1, n, !(numbpart(k) % 2)); \\ Michel Marcus, Feb 24 2023

Formula

a(n) = n + 1 - A071754(n).